As is known in the art of tracking personal items with wireless devices, some systems, such disclosed in U.S. Pat. No. 5,796,338, may be used to alert someone when his cellular phone is misplaced or been moved away from his possession. As shown in FIG. 1, a cellular phone 11 can be tracked by a pager 12, across a network 13, such as a “pager network” established and maintained by a third party service provider. In operation, this prior art alert utilizes the pager and the service provider's network to links a message transmission 14 from the cell phone device, and the cellular phone to the pager. The alert is sent by the user's cell phone to the pager, which is carried by the user to track their cell phone.
A fundamental problem with this prior alert system occurs if the pager 12 is misplaced, or if the user is in an area not covered by the network 13, or equivalent cellular phone network. The alert may fail to reach the user because of the possible delay in the delivery of alerting message from cellular phone 11 to the pager, preventing the user from a timely recovery of the valuable cellular phone. Additionally, this prior alert system may be rendered ineffective because the misplaced cellular phone must be manually operated, to trigger the sending of the message transmission 14 as the alerting signal. The timing of such a trigger is not guaranteed to occur soon enough to locate the cellular phone, nor is the trigger guaranteed to occur at all.
FIG. 2 shows another type of prior art system, sold as a “Now You Can Find It”®, by The Sharper Image Corp., of San Francisco, Calif., USA. This prior art system uses the transmission of radio frequency signal from a base device 20 to help someone locate items, to which a receiving device 21 are attached to. The receiving device is a radio frequency receiver, typically including at least a first disc 22 and a second disc 23. The first disc and the second disc are attached to items that are typically valuable and easily misplaced. The first disc and the second disc are independently capable of emitting a sounding alarm, when either receives a radio signal 24, at a pre-determined frequency from the base device. The base device is inactive most of the time. A failing of this prior alert system occurs if the receiving device disc is out of range and not able to receive the radio signal from base device. This scenario most likely occurs if someone walks away with the valuable item of interest, or if the receiving device is out of battery power, or receiving device's power source is otherwise disabled or disconnected. In practice, this scenario is very likely to happen, because the receiving device is inactive most of the time. It is very unlikely for the user to find out the “out-of-battery” condition prior to the item of interest being misplaced.
A wireless tracking device is needed that is able to overcome these shortcomings of prior devices. The present invention addresses these shortcomings and disadvantages, improving upon the design and operation of prior wireless tracking devices to provide a wireless tracking system that prevents “out of range” and “out of battery” failures. Furthermore, the present invention will be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings.